The pathology and causes of tissue eosinophilia in the gastrointestinal tract

Abstract

Eosinophilic inflammation in the gastrointestinal tract may occur as a primary eosinophilic disorder or as a secondary response with other causes. Primary eosinophilic gastrointestinal disorders (EGIDs) are Th2-mediated allergic diseases that overlap pathogenetically with atopic conditions involving other organs. The pathological diagnosis of primary EGIDs can be challenging, as the quantity of eosinophils considered to be 'abnormal' is difficult to define, and the diagnosis, by definition, requires exclusion of the far more common secondary causes. Our understanding of the basic biology and natural history of eosinophilic oesophagitis has advanced considerably over the last decade, whereas other EGIDs have proven more difficult to characterize; nonetheless, some recent advances have been made. This review summarizes current knowledge regarding the clinical presentation, diagnosis, natural history and treatment of EGIDs, including eosinophilic oesophagitis. We also draw attention to the numerous secondary causes of tissue eosinophilia in the gastrointestinal tract, and suggest a practical approach to the histological assessment, diagnosis and reporting of EGIDs.

In vivo Evidence for Partial Activation of Eosinophils via the Histamine H4-Receptor: Adoptive Transfer Experiments Using Eosinophils From H4R−/− and H4R+/+ Mice

“…Elevated numbers of eosinophils and high histamine concentrations are found in inflamed colon tissues of patients suffering from inflammatory bowel diseases (IBD), which are idiopathic, chronic-recurring diseases of the gastrointestinal system with the two major clinical manifestations ulcerative colitis (UC) and Crohn's disease (CD) ( 9 – 11 ), as well as in cola of mice subjected to chemically induced colitis models ( 12 , 13 ). While antagonists at the H 1 R are without clinical relevance in the treatment of IBD or in animal models, blockade of histamine production or H 4 R function is beneficial in specific colitis models, such as dextran sodium sulfate (DSS)-induced colitis in mice ( 14 – 18 ).…”

Eosinophilic gastroenteritis: Atypical cause for chronic diarrhea in human immunodeficiency virus-associated immunosuppression

“…[2] Large-scale population studies in the US have estimated the prevalence of EGE to be 28/100,000 persons. [4] Eosinophilic gastrointestinal disorders affect all ethnic groups between 20 and 50 years of age but more commonly around the third decade of life. [5] Unlike in the esophagus, baseline eosinophils are detected in the stomach and intestine under healthy conditions as a part of the host-defense mechanism.…”

Beyond Helicobacter: dealing with other variants of gastritis—an algorithmic approach

“…Increased numbers of duodenal IELs are present in both H. pylori gastritis and NSAID-associated gastritis, but in both the intraepithelial lymphocytosis is mild, and often occurs primarily at the sides of the villi; they cannot be distinguished morphologically. 47 In summary, algorithmically, a corpus-predominant LG, especially with neutrophils, should be idiopathic or Helicobacter-related. Diffuse intraepithelial pangastritis should prompt a search for NSAID ingestion, and, if duodenal biopsies are present, there may be intraepithelial lymphocytosis at the sides of the villi, but other features of upper (or lower) NSAID pathology (reactive changes, erosion, ulcers, ileitis, and colitis) may be present.…”